Corrosion-resistant neodymium-iron-boron permanent magnet material and method for producing the same

Abstract

The application discloses a kind of corrosion-resistant neodymium-iron-boron permanent magnet materials and preparation method thereof, it is related to permanent magnet material technical field, including neodymium-iron-boron permanent magnet material matrix and corrosion-resistant protective coating coated in the outer surface of permanent magnet material matrix;The neodymium-iron-boron permanent magnet material matrix is made of the following components by weight percentage: 23-25wt% Nd, 3.0-5.0wt% other rare earth elements, 0.8-1.2wt% B, 0.5-2.2wt% Ni, 0.01-0.05wt% Zn, 0.5-1.2wt% Ga, 0.03-0.06wt% V, 0.01-0.03wt% Si, 0.01-0.02wt% Ba, the balance is Fe.The corrosion-resistant neodymium-iron-boron permanent magnet material disclosed in the application has excellent corrosion resistance and comprehensive magnetic properties.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet materials technology, and in particular to a corrosion-resistant neodymium iron boron permanent magnet material and its preparation method. Background Technology

[0002] Neodymium iron boron (NdFeB) permanent magnets, as the third generation of permanent magnet materials, have been widely used in microwave technology, audio-visual technology, electrical engineering, instrumentation technology, computer technology, magnetic separation technology, aerospace, and the automotive industry due to their excellent magnetic properties and low price, earning them the title of "King of Magnets." With the further promotion of NdFeB permanent magnets in high-tech applications, the requirements for the comprehensive performance of these products are constantly increasing, especially their corrosion resistance.

[0003] Neodymium iron boron (NdFeB) permanent magnets are multiphase powder alloys composed of a main phase, a boron-rich phase, and a Nd-rich phase. The Nd-rich phase surrounds the main phase as a grain boundary phase (mainly concentrated at triangular grain boundaries), while the boron-rich phase also exists within the grain boundaries. The differences in the chemical composition of each phase result in different chemical potentials, which easily form corrosion currents under humid and hot conditions, causing intergranular corrosion. In addition, the oxidation corrosion and hydrogen absorption pulverization of the Nd-rich phase are also the main causes of magnet corrosion. Generally, when the magnet is placed in a room temperature and dry environment, the presence of a large amount of elemental Nd (with poor chemical stability) in the Nd-rich phase during sintering makes it prone to oxidation reactions to produce Nd₂O₃, causing oxidation corrosion. Under higher temperature and humidity conditions, the Nd in the Nd-rich phase is easily oxidized to Nd(OH)₃, producing H₂, which then leads to hydrogen absorption pulverization, making corrosion even more severe and seriously limiting its application in important fields.

[0004] To address the aforementioned issues, Chinese invention patent document CN102361359B discloses a corrosion-resistant neodymium iron boron permanent magnet for motors, wherein the neodymium iron boron material has a Re composition. α B β M x N y Fe 1-α-β-x-y The composition is as follows: Re represents rare earth elements, a mixture of Nd, Dy, and Ho, with Nd comprising 50% by weight, and Dy and Ho each comprising 25%; M represents added elements, including Co and Cu; N represents added elements, including one or more elements selected from Ti, V, Cr, Mn, Ni, Zr, Nb, Mo, and Bi; α, β, x, and y represent the atomic percentage content of each element; wherein 20% ≤ α ≤ 25%, 5% ≤ β ≤ 12%, 3% ≤ x ≤ 7%, and 5% ≤ y ≤ 10%. This NdFeB permanent magnet improves corrosion resistance and thermal stability while maintaining magnetic properties; however, its corrosion resistance and overall magnetic properties still need further improvement.

[0005] Therefore, developing a corrosion-resistant NdFeB permanent magnet material with excellent corrosion resistance and comprehensive magnetic properties, and its preparation method, meets market demand, has broad market value and application prospects, and is of great significance to promoting the further development of NdFeB permanent magnet materials. Summary of the Invention

[0006] The main objective of this invention is to provide a corrosion-resistant neodymium iron boron permanent magnet material with excellent corrosion resistance and comprehensive magnetic properties, and its preparation method.

[0007] To achieve the above objectives, this invention provides a corrosion-resistant neodymium iron boron (NdFeB) permanent magnet material, comprising a NdFeB permanent magnet material matrix and a corrosion-resistant protective coating covering the outer surface of the permanent magnet material matrix; the NdFeB permanent magnet material matrix is ​​composed of the following components by weight percentage: 23-25 ​​wt% Nd, 3.0-5.0 wt% other rare earth elements, 0.8-1.2 wt% B, 0.5-2.2 wt% Ni, 0.01-0.05 wt% Zn, 0.5-1.2 wt% Ga, 0.03-0.06 wt% V, 0.01-0.03 wt% Si, and 0.01-0.02 wt% ... The coating contains wt% Ba, with the balance being Fe; the corrosion-resistant protective coating is made from the following raw materials in parts by weight: 50-70 parts of 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer, 5-8 parts of 4,4'-diaminodiphenyl sulfone, 5-8 parts of graphene oxide, 10-15 parts of amino-terminated crystalline polyarylether ketone, 1-2 parts of defoamer, 1-3 parts of dispersant, and 40-50 parts of solvent.

[0008] Preferably, the solvent is at least one selected from N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0009] Preferably, the defoamer is one or more of tributyl phosphate, defoamer Deqian 3100, and defoamer BYK088; the dispersant is at least one of dispersant LD-1108 and dispersant HH2016D.

[0010] Preferably, there are no special requirements regarding the source of the amino-terminated crystalline polyarylether ketone. In one embodiment of the present invention, the amino-terminated crystalline polyarylether ketone is prepared according to the method in Example 1 of Chinese Patent Document CN113105620B.

[0011] Preferably, the graphene oxide has an average diameter of 3-10 μm and an average thickness of 0.55-2.0 nm, and is provided by Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences.

[0012] Preferably, the preparation method of the 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer includes the following steps: 2,3,4,5,6-pentafluorostyrene, 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, 2-(1- Propylene-2-yl)benzo[d]oxazole and an initiator were added to a high-boiling-point solvent and stirred at 60-70°C for 3-5 hours under an inert gas atmosphere. The polymer was then precipitated in water and washed 3-6 times with ethanol. Finally, it was dried in a vacuum drying oven at 80-90°C to constant weight to obtain a 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer.

[0013] Preferably, the mass ratio of 2,3,4,5,6-pentafluorostyrene, 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, 2-(1-propen-2-yl)benzo[d]oxazole, initiator, and high-boiling solvent is 0.5:(0.8-1.2):(3-5):(0.3-0.6):(0.06-0.08):(25-35).

[0014] Preferably, the initiator is azobisisobutyronitrile; the high-boiling-point solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone; and the inert gas is any one of nitrogen, helium, neon, and argon.

[0015] Preferably, the other rare earth elements are a mixture of Gd, Tb, and Dy in a mass ratio of 2:1:(1-3).

[0016] Another object of the present invention is to provide a method for preparing the corrosion-resistant NdFeB permanent magnet material, comprising the following steps:

[0017] Step S1: Prepare the NdFeB permanent magnet matrix by weight percentage of each component, and then use vacuum induction rapid solidification casting technology to prepare NdFeB permanent magnet matrix rapid solidification casting sheet;

[0018] Step S2: After hydrogen explosion or mechanical crushing, the powder is made into micro powder with an average particle size of 1-4 μm by ball milling or air jet milling.

[0019] Step S3: Orient the micro powder with a magnetic field and press it into shape to obtain a blank NdFeB permanent magnet material matrix;

[0020] Step S4: After high-temperature sintering and tempering treatment, a neodymium iron boron permanent magnet material matrix is ​​obtained.

[0021] Step S5: After mixing all the raw materials of the corrosion-resistant protective coating evenly, coat it onto the outer surface of the NdFeB permanent magnet material substrate with a coating thickness of 0.2mm, and then dry it to obtain the corrosion-resistant NdFeB permanent magnet material.

[0022] Preferably, the magnetic field orientation and static pressing in step S3 specifically involves: orientation molding under a magnetic field strength of 1-3T, a pressure of 30-100MPa, and a nitrogen atmosphere, followed by cold isostatic pressing at an isostatic pressure of 270-320MPa for 3-5 minutes.

[0023] Preferably, the high-temperature sintering in step S4 is carried out in a vacuum sintering furnace, with a sintering temperature of 1000-1150℃ and a sintering time of 2-4 hours.

[0024] Preferably, the tempering treatment in step S4 specifically involves: holding at 850-930℃ for 1-3 hours for a first-stage tempering treatment, and then holding at 450-600℃ for 2-4 hours for a second-stage tempering treatment.

[0025] Preferably, the drying in step S5 is carried out at 100-120°C for 3-5 hours.

[0026] Due to the application of the above technical solution, the present invention has the following beneficial effects:

[0027] (1) The method for preparing corrosion-resistant neodymium iron boron permanent magnet materials disclosed in this invention can be achieved using conventional equipment without the need to modify existing production lines. It requires little capital investment, has high preparation efficiency and yield, and is suitable for continuous large-scale production.

[0028] (2) The corrosion-resistant NdFeB permanent magnet material disclosed in this invention is made of the following components by weight percentage: 23-25wt% Nd, 3.0-5.0wt% other rare earth elements, 0.8-1.2wt% B, 0.5-2.2wt% Ni, 0.01-0.05wt% Zn, 0.5-1.2wt% Ga, 0.03-0.06wt% V, 0.01-0.03wt% Si, 0.01-0.02wt% Ba, with the balance being Fe. Through the synergistic effect of the components, the grains can be refined, the growth of each group of grains can be inhibited, the microstructure can be improved, and the coercivity and stability can be enhanced, resulting in a permanent magnet material with excellent corrosion resistance and comprehensive magnetic properties.

[0029] (3) The corrosion-resistant neodymium iron boron permanent magnet material disclosed in this invention has a corrosion-resistant protective coating on the outer surface of the permanent magnet material substrate, which can significantly improve the corrosion resistance of the permanent magnet material, and improve its service life and application range; the corrosion-resistant protective coating is made of the following raw materials in parts by weight: 50-70 parts of 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer, 5-8 parts of 4,4'-diaminodiphenyl sulfone, 5-8 parts of graphene oxide, 10-15 parts of amino-terminated crystalline polyarylether ketone, 1-2 parts of defoamer, 1-3 parts of dispersant, and 40-50 parts of solvent. The simultaneous introduction of pentafluorobenzene, triazine ketone, carbazole, benzo[d]oxazole, sulfone, and polyarylether ketone structures into the coating, under the multiple effects of electronic effects, steric hindrance effects, and conjugation effects, results in a coating with sufficient corrosion resistance, long service life, and excellent weather resistance and aging resistance. The epoxy groups on the 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer can undergo an epoxy ring-opening reaction with the amino groups on 4,4'-diaminodiphenyl sulfone and amino-terminated crystalline polyarylether ketone to form an interpenetrating network structure, further improving corrosion resistance and extending service life. Detailed Implementation

[0030] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0031] Example 1

[0032] A corrosion-resistant neodymium iron boron (NdFeB) permanent magnet material includes a NdFeB permanent magnet material matrix and a corrosion-resistant protective coating covering the outer surface of the permanent magnet material matrix; the NdFeB permanent magnet material matrix is ​​composed of the following components by weight percentage: 23 wt% Nd, 3.0 wt% other rare earth elements, 0.8 wt% B, 0.5 wt% Ni, 0.01 wt% Zn, 0.5 wt% Ga, 0.03 wt% V, 0.01 wt% Si, 0.01 wt% Ba, with the balance being Fe; the corrosion-resistant... The corrosion protection coating is made from the following raw materials in parts by weight: 50 parts of 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer, 5 parts of 4,4'-diaminodiphenyl sulfone, 5 parts of graphene oxide, 10 parts of amino-terminated crystalline polyarylether ketone, 1 part of defoamer, 1 part of dispersant, and 40 parts of solvent.

[0033] The solvent is N,N-dimethylformamide; the defoamer is tributyl phosphate; the dispersant is dispersant LD-1108; the amino-terminated crystalline polyarylether ketone is prepared according to the method in Example 1 of Chinese Patent Document CN113105620B; the graphene oxide has an average diameter of 3-10 μm and an average thickness of 0.55-2.0 nm, and is provided by Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences.

[0034] The preparation method of the 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer includes the following steps: 2,3,4,5,6-pentafluorostyrene, 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, 2-(1-propen-2-yl)benzo[d]oxazole, and an initiator are added to a high-boiling-point solvent. The mixture is stirred and reacted at 60°C for 3 hours under an inert gas atmosphere. The polymer is then precipitated in water, washed three times with ethanol, and finally placed in a vacuum drying oven at 80°C. Drying to constant weight yields 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer; the 2,3,4,5,6-pentafluorostyrene, 1,3-bis(epoxyethylenemethyl) The copolymer was prepared in a mass ratio of 0.5:0.8:3:0.3:0.06:25, consisting of 5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, 2-(1-propen-2-yl)benzo[d]oxazole, an initiator, and a high-boiling solvent. The initiator was azobisisobutyronitrile (AIB), the high-boiling solvent was dimethyl sulfoxide (DMSO), and the inert gas was nitrogen. GPC testing showed that the copolymer had a Mn of 18930 g / mol and a Mn of... W / M n =1.228; EDX elemental analysis and weight change calculations confirmed that the mass ratio of the structural units introduced by 2,3,4,5,6-pentafluorostyrene, 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, and 2-(1-propen-2-yl)benzo[d]oxazole in the copolymer was 0.48:0.8:2.9:0.28.

[0035] The other rare earth elements are a mixture of Gd, Tb, and Dy in a mass ratio of 2:1:1.

[0036] A method for preparing the corrosion-resistant NdFeB permanent magnet material includes the following steps:

[0037] Step S1: Prepare the NdFeB permanent magnet matrix by weight percentage of each component, and then use vacuum induction rapid solidification casting technology to prepare NdFeB permanent magnet matrix rapid solidification casting sheet;

[0038] Step S2: After hydrogen explosion or mechanical crushing, the powder is made into micro powder with an average particle size of 4μm by ball milling or air jet milling.

[0039] Step S3: Orient the micro powder with a magnetic field and press it into shape to obtain a blank NdFeB permanent magnet material matrix;

[0040] Step S4: After high-temperature sintering and tempering treatment, a neodymium iron boron permanent magnet material matrix is ​​obtained.

[0041] Step S5: After mixing all the raw materials of the corrosion-resistant protective coating evenly, coat it onto the outer surface of the NdFeB permanent magnet material substrate with a coating thickness of 0.2mm, and then dry it to obtain the corrosion-resistant NdFeB permanent magnet material.

[0042] The magnetic field orientation and static pressing in step S3 are specifically as follows: orientation is performed under the conditions of magnetic field strength of 1T, pressure of 30MPa, and nitrogen atmosphere, followed by cold isostatic pressing at 270MPa for 3 minutes.

[0043] The high-temperature sintering described in step S4 is carried out in a vacuum sintering furnace at a sintering temperature of 1000℃ for 2 hours. The tempering treatment specifically involves holding the temperature at 850℃ for 1 hour for a first-stage tempering treatment, followed by holding the temperature at 450℃ for 2 hours for a second-stage tempering treatment.

[0044] The drying process described in step S5 involves drying at 100°C for 3 hours.

[0045] Example 2

[0046] A corrosion-resistant neodymium iron boron (NdFeB) permanent magnet material includes a NdFeB permanent magnet material matrix and a corrosion-resistant protective coating covering the outer surface of the permanent magnet material matrix; the NdFeB permanent magnet material matrix is ​​composed of the following components by weight percentage: 24 wt% Nd, 3.5 wt% other rare earth elements, 0.9 wt% B, 0.9 wt% Ni, 0.02 wt% Zn, 0.8 wt% Ga, 0.045 wt% V, 0.02 wt% Si, 0.015 wt% Ba, with the balance being Fe; the corrosion-resistant... The protective coating is made from the following raw materials in parts by weight: 60 parts of 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer, 6.5 parts of 4,4'-diaminodiphenyl sulfone, 6.5 parts of graphene oxide, 13 parts of amino-terminated crystalline polyarylether ketone, 1.5 parts of defoamer, 2 parts of dispersant, and 45 parts of solvent.

[0047] The solvent is N,N-dimethylacetamide; the defoamer is Deqian 3100; the dispersant is HH2016D; the amino-terminated crystalline polyarylether ketone is prepared according to the method in Example 1 of Chinese Patent Document CN113105620B; the graphene oxide has an average diameter of 3-10 μm and an average thickness of 0.55-2.0 nm, and is provided by Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences.

[0048] The preparation method of the 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer includes the following steps: 2,3,4,5,6-pentafluorostyrene, 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, 2-(1-propen-2-yl)benzo[d]oxazole, and an initiator are added to a high-boiling-point solvent. The reaction is carried out under an inert gas atmosphere at 63°C with stirring for 3.5 hours. The polymer is then precipitated in water, washed four times with ethanol, and finally dried in a vacuum drying oven at 83°C. To constant weight, 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer was obtained; the 2,3,4,5,6-pentafluorostyrene, 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer was obtained; The mass ratio of (-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, 2-(1-propen-2-yl)benzo[d]oxazole, initiator, and high-boiling solvent is 0.5:0.9:3.5:0.4:0.065:27; the initiator is azobisisobutyronitrile; the high-boiling solvent is N,N-dimethylformamide; and the inert gas is helium.

[0049] The other rare earth elements are a mixture of Gd, Tb, and Dy in a mass ratio of 2:1:1.5.

[0050] A method for preparing the corrosion-resistant NdFeB permanent magnet material includes the following steps:

[0051] Step S1: Prepare the NdFeB permanent magnet matrix by weight percentage of each component, and then use vacuum induction rapid solidification casting technology to prepare NdFeB permanent magnet matrix rapid solidification casting sheet;

[0052] Step S2: After hydrogen explosion or mechanical crushing, the powder is made into micro powder with an average particle size of 3μm by ball milling or air jet milling.

[0053] Step S3: Orient the micro powder with a magnetic field and press it into shape to obtain a blank NdFeB permanent magnet material matrix;

[0054] Step S4: After high-temperature sintering and tempering treatment, a neodymium iron boron permanent magnet material matrix is ​​obtained.

[0055] Step S5: After mixing all the raw materials of the corrosion-resistant protective coating evenly, coat it onto the outer surface of the NdFeB permanent magnet material substrate with a coating thickness of 0.2mm, and then dry it to obtain the corrosion-resistant NdFeB permanent magnet material.

[0056] The magnetic field orientation and static pressing in step S3 are specifically as follows: orientation is performed under the conditions of magnetic field strength of 2.5T, pressure of 60MPa and nitrogen atmosphere, followed by cold isostatic pressing at 290MPa for 3.5 minutes.

[0057] The high-temperature sintering in step S4 is carried out in a vacuum sintering furnace at a sintering temperature of 1050℃ for 2.5 hours. The tempering treatment is specifically as follows: a first-stage tempering treatment is performed by holding at 880℃ for 2 hours, followed by a second-stage tempering treatment by holding at 500℃ for 2.5 hours.

[0058] The drying process described in step S5 involves drying at 105°C for 3.5 hours.

[0059] Example 3

[0060] A corrosion-resistant neodymium iron boron (NdFeB) permanent magnet material includes a NdFeB permanent magnet material matrix and a corrosion-resistant protective coating covering the outer surface of the permanent magnet material matrix; the NdFeB permanent magnet material matrix is ​​composed of the following components by weight percentage: 24 wt% Nd, 4.0 wt% other rare earth elements, 1 wt% B, 1.6 wt% Ni, 0.035 wt% Zn, 0.9 wt% Ga, 0.045 wt% V, 0.02 wt% Si, 0.015 wt% Ba, with the balance being Fe; the corrosion-resistant protective coating... The protective coating is made from the following raw materials in parts by weight: 60 parts of 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer, 6.5 parts of 4,4'-diaminodiphenyl sulfone, 6.5 parts of graphene oxide, 13 parts of amino-terminated crystalline polyarylether ketone, 1.5 parts of defoamer, 2 parts of dispersant, and 45 parts of solvent.

[0061] The solvent is N-methylpyrrolidone; the defoamer is defoamer BYK088; the dispersant is dispersant LD-1108; the amino-terminated crystalline polyarylether ketone is prepared according to the method in Example 1 of Chinese Patent Document CN113105620B; the graphene oxide has an average diameter of 3-10 μm and an average thickness of 0.55-2.0 nm, and is provided by Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences.

[0062] The preparation method of the 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer includes the following steps: 2,3,4,5,6-pentafluorostyrene, 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, 2-(1-propen-2-yl)benzo[d]oxazole, and an initiator are added to a high-boiling-point solvent. The mixture is stirred and reacted at 65°C for 4 hours under an inert gas atmosphere. The polymer is then precipitated in water, washed five times with ethanol, and finally placed in a vacuum drying oven at 85°C. Drying to constant weight yields 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer; the 2,3,4,5,6-pentafluorostyrene, 1,3-bis(epoxyethylenemethyl)- The mass ratio of 5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, 2-(1-propen-2-yl)benzo[d]oxazole, initiator, and high-boiling solvent is 0.5:1:4:0.45:0.07:30; the initiator is azobisisobutyronitrile; the high-boiling solvent is N-methylpyrrolidone; and the inert gas is neon.

[0063] The other rare earth elements are a mixture of Gd, Tb, and Dy in a mass ratio of 2:1:2.

[0064] A method for preparing the corrosion-resistant NdFeB permanent magnet material includes the following steps:

[0065] Step S1: Prepare the NdFeB permanent magnet matrix by weight percentage of each component, and then use vacuum induction rapid solidification casting technology to prepare NdFeB permanent magnet matrix rapid solidification casting sheet;

[0066] Step S2: After hydrogen explosion or mechanical crushing, the powder is made into micro powder with an average particle size of 2μm by ball milling or air jet milling.

[0067] Step S3: Orient the micro powder with a magnetic field and press it into shape to obtain a blank NdFeB permanent magnet material matrix;

[0068] Step S4: After high-temperature sintering and tempering treatment, a neodymium iron boron permanent magnet material matrix is ​​obtained.

[0069] Step S5: After mixing all the raw materials of the corrosion-resistant protective coating evenly, coat it onto the outer surface of the NdFeB permanent magnet material substrate with a coating thickness of 0.2mm, and then dry it to obtain the corrosion-resistant NdFeB permanent magnet material.

[0070] The magnetic field orientation and static pressing in step S3 are specifically as follows: orientation is performed under the conditions of magnetic field strength of 2T, pressure of 80MPa, and nitrogen atmosphere, followed by cold isostatic pressing at 300MPa for 4 minutes.

[0071] The high-temperature sintering described in step S4 is carried out in a vacuum sintering furnace at a sintering temperature of 1090℃ for 3 hours. The tempering treatment specifically involves a first-stage tempering treatment at 900℃ for 2 hours, followed by a second-stage tempering treatment at 530℃ for 3 hours.

[0072] The drying process described in step S5 involves drying at 110°C for 4 hours.

[0073] Example 4

[0074] A corrosion-resistant neodymium iron boron (NdFeB) permanent magnet material includes a NdFeB permanent magnet material matrix and a corrosion-resistant protective coating covering the outer surface of the permanent magnet material matrix; the NdFeB permanent magnet material matrix is ​​composed of the following components by weight percentage: 24.5 wt% Nd, 4.5 wt% other rare earth elements, 1.1 wt% B, 2.1 wt% Ni, 0.04 wt% Zn, 1.1 wt% Ga, 0.05 wt% V, 0.025 wt% Si, 0.018 wt% Ba, with the balance being Fe; the corrosion-resistant... The protective coating is made from the following raw materials in parts by weight: 65 parts of 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer, 7.5 parts of 4,4'-diaminodiphenyl sulfone, 7.5 parts of graphene oxide, 14 parts of amino-terminated crystalline polyarylether ketone, 1.8 parts of defoamer, 2.5 parts of dispersant, and 48 parts of solvent.

[0075] The solvent is a mixture of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide in a mass ratio of 1:1:3:2; the defoamer is a mixture of tributyl phosphate, defoamer Deqian 3100, and defoamer BYK088 in a mass ratio of 1:3:2; the dispersant is a mixture of dispersant LD-1108 and dispersant HH2016D in a mass ratio of 3:5; the amino-terminated crystalline polyaryletherketone is prepared according to the method in Example 1 of Chinese Patent Document CN113105620B; the graphene oxide has an average diameter of 3-10 μm and an average thickness of 0.55-2.0 nm, and was provided by Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences.

[0076] The method for preparing the 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer includes the following steps: mixing 2,3,4,5,6-pentafluorostyrene, 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole. (-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, 2-(1-propen-2-yl)benzo[d]oxazole, and an initiator were added to a high-boiling solvent. The mixture was stirred at 68°C for 4.5 hours under an inert atmosphere. The polymer was then precipitated in water, washed six times with ethanol, and finally dried at 88°C in a vacuum oven to constant weight to obtain 2,3,4,5,6- Pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer; the 2,3,4,5,6-pentafluorostyrene, 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer; The mass ratio of 3H,5H)-trione, N-vinylcarbazole, 2-(1-propen-2-yl)benzo[d]oxazole, initiator, and high-boiling solvent is 0.5:1.1:4.5:0.55:0.075:33; the initiator is azobisisobutyronitrile; the high-boiling solvent is a mixture of dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone in a mass ratio of 1:5:2; and the inert gas is argon.

[0077] The other rare earth elements are a mixture of Gd, Tb, and Dy in a mass ratio of 2:1:2.5.

[0078] A method for preparing the corrosion-resistant NdFeB permanent magnet material includes the following steps:

[0079] Step S1: Prepare the NdFeB permanent magnet matrix by weight percentage of each component, and then use vacuum induction rapid solidification casting technology to prepare NdFeB permanent magnet matrix rapid solidification casting sheet;

[0080] Step S2: After hydrogen explosion or mechanical crushing, the powder is made into micro powder with an average particle size of 1.5 μm by ball milling or air jet milling.

[0081] Step S3: Orient the micro powder with a magnetic field and press it into shape to obtain a blank NdFeB permanent magnet material matrix;

[0082] Step S4: After high-temperature sintering and tempering treatment, a neodymium iron boron permanent magnet material matrix is ​​obtained.

[0083] Step S5: After mixing all the raw materials of the corrosion-resistant protective coating evenly, coat it onto the outer surface of the NdFeB permanent magnet material substrate with a coating thickness of 0.2mm, and then dry it to obtain the corrosion-resistant NdFeB permanent magnet material.

[0084] The magnetic field orientation and static pressing in step S3 are specifically as follows: orientation is performed under the conditions of magnetic field strength of 2.5T, pressure of 90MPa and nitrogen atmosphere, followed by cold isostatic pressing at 310MPa for 4.5 minutes.

[0085] The high-temperature sintering in step S4 is carried out in a vacuum sintering furnace at a sintering temperature of 1120℃ for 3.5 hours. The tempering treatment is specifically as follows: a first-stage tempering treatment is performed by holding at 920℃ for 2.5 hours, followed by a second-stage tempering treatment by holding at 580℃ for 3.5 hours.

[0086] The drying process described in step S5 involves drying at 115°C for 4.5 hours.

[0087] Example 5

[0088] A corrosion-resistant neodymium iron boron (NdFeB) permanent magnet material includes a NdFeB permanent magnet material matrix and a corrosion-resistant protective coating covering the outer surface of the permanent magnet material matrix; the NdFeB permanent magnet material matrix is ​​composed of the following components by weight percentage: 25 wt% Nd, 5.0 wt% other rare earth elements, 1.2 wt% B, 2.2 wt% Ni, 0.05 wt% Zn, 1.2 wt% Ga, 0.06 wt% V, 0.03 wt% Si, 0.02 wt% Ba, with the balance being Fe; the corrosion-resistant... The corrosion protection coating is made from the following raw materials in parts by weight: 70 parts of 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer, 8 parts of 4,4'-diaminodiphenyl sulfone, 8 parts of graphene oxide, 15 parts of amino-terminated crystalline polyarylether ketone, 2 parts of defoamer, 3 parts of dispersant, and 50 parts of solvent.

[0089] The solvent is dimethyl sulfoxide; the defoamer is tributyl phosphate; the dispersant is dispersant LD-1108; the amino-terminated crystalline polyarylether ketone is prepared according to the method in Example 1 of Chinese Patent Document CN113105620B; the graphene oxide has an average diameter of 3-10 μm and an average thickness of 0.55-2.0 nm, and is provided by Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences.

[0090] The preparation method of the 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer includes the following steps: 2,3,4,5,6-pentafluorostyrene, 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, 2-(1-propen-2-yl)benzo[d]oxazole, and an initiator are added to a high-boiling-point solvent. The mixture is stirred and reacted at 70°C for 5 hours under an inert gas atmosphere. The polymer is then precipitated in water, followed by washing the precipitated polymer six times with ethanol. Finally, the polymer is placed in a vacuum drying oven at 90°C. Drying to constant weight yields 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer; the 2,3,4,5,6-pentafluorostyrene, 1,3-bis(epoxyethylenemethyl) The mass ratio of 5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, 2-(1-propen-2-yl)benzo[d]oxazole, initiator, and high-boiling solvent is 0.5:1.2:5:0.6:0.08:35; the initiator is azobisisobutyronitrile; the high-boiling solvent is dimethyl sulfoxide; and the inert gas is nitrogen.

[0091] The other rare earth elements are a mixture of Gd, Tb, and Dy in a mass ratio of 2:1:2.5.

[0092] A method for preparing the corrosion-resistant NdFeB permanent magnet material includes the following steps:

[0093] Step S1: Prepare the NdFeB permanent magnet matrix by weight percentage of each component, and then use vacuum induction rapid solidification casting technology to prepare NdFeB permanent magnet matrix rapid solidification casting sheet;

[0094] Step S2: After hydrogen explosion or mechanical crushing, the powder is made into micro powder with an average particle size of 1μm by ball milling or air jet milling.

[0095] Step S3: Orient the micro powder with a magnetic field and press it into shape to obtain a blank NdFeB permanent magnet material matrix;

[0096] Step S4: After high-temperature sintering and tempering treatment, a neodymium iron boron permanent magnet material matrix is ​​obtained.

[0097] Step S5: After mixing all the raw materials of the corrosion-resistant protective coating evenly, coat it onto the outer surface of the NdFeB permanent magnet material substrate with a coating thickness of 0.2mm, and then dry it to obtain the corrosion-resistant NdFeB permanent magnet material.

[0098] The magnetic field orientation and static pressing in step S3 are specifically as follows: orientation is performed under the conditions of magnetic field strength of 3T, pressure of 100MPa and nitrogen atmosphere, followed by cold isostatic pressing at 320MPa for 5 minutes.

[0099] The high-temperature sintering described in step S4 is carried out in a vacuum sintering furnace at a sintering temperature of 1150℃ for 4 hours. The tempering treatment specifically involves holding the temperature at 930℃ for 3 hours for a first-stage tempering treatment, followed by holding the temperature at 600℃ for 4 hours for a second-stage tempering treatment.

[0100] The drying process described in step S5 involves drying at 120°C for 5 hours.

[0101] Comparative Example 1

[0102] This invention provides a corrosion-resistant neodymium iron boron permanent magnet material, which is similar to that of Example 1, except that it does not contain V, Ba and amino-terminated crystalline polyaryletherketone.

[0103] Comparative Example 2

[0104] This invention provides a corrosion-resistant neodymium iron boron permanent magnet material, which is similar to Example 1, except that Si and Zn are not added, and N-vinylcarbazole and 2,3,4,5,6-pentafluorostyrene are not added in the preparation process of 2,3,4,5,6-pentafluorostyrene / 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer.

[0105] To further illustrate the beneficial technical effects of the corrosion-resistant NdFeB permanent magnet materials prepared in the various embodiments of the present invention, relevant performance tests were conducted on the corrosion-resistant NdFeB permanent magnet materials prepared in each example. The test results are shown in Table 1. The test methods are as follows: The comprehensive magnetic properties were tested according to the magnetic test method for permanent magnet (hard magnet) materials in GB / T3217-2013; the corrosion resistance was tested by conducting a neutral salt spray test on the corrosion-resistant NdFeB permanent magnet materials. A 5wt% sodium chloride aqueous solution was used to spray the test material with salt spray at a temperature of 30°C, and the corrosion was observed.

[0106] Table 1. Performance test results of corrosion-resistant NdFeB permanent magnet materials

[0107]

[0108] As can be seen from Table 1, the corrosion-resistant NdFeB permanent magnet material disclosed in the embodiments of the present invention has superior comprehensive magnetic properties and corrosion resistance compared with the comparative product. The addition of V, Ba, amino-terminated crystalline polyaryletherketone, Si, Zn, N-vinylcarbazole and 2,3,4,5,6-pentafluorostyrene are all beneficial to improving the above properties.

[0109] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A corrosion resistant Nd-Fe-B permanent magnet material, characterized in that, The application relates to a neodymium-iron-boron permanent magnet material base and a corrosion-resistant protective coating coated on the outer surface of the permanent magnet material base; the neodymium-iron-boron permanent magnet material base is made of the following components in percentage by weight: 23-25wt% of Nd, 3.0-5.0wt% of other rare earth elements, 0.8-1.2wt% of B, 0.5-2.2wt% of Ni, 0.01-0.05wt% of Zn, 0.5-1.2wt% of Ga, 0.03-0.06wt% of V, 0.01-0.03wt% of Si, 0.01-0.02wt% of Ba, and the balance of Fe; the corrosion-resistant protective coating is made of the following raw materials in parts by weight: 2,3,4,5,6-pentafluorostyrene / 1,3-bis(oxymethylene methyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer 50-70 parts, 4,4'-diamino diphenyl sulfone 5-8 parts, graphene oxide 5-8 parts, amino-terminated crystalline polyaryletherketone 10-15 parts, defoaming agent 1-2 parts, dispersant 1-3 parts, and solvent 40-50 parts.

2. The corrosion resistant NdFeB permanent magnetic material according to claim 1, characterized in that, The solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide; the defoaming agent is one or more of tributyl phosphate, defoaming agent Decon 3100 and defoaming agent BYK088; and the dispersant is at least one of dispersant LD-1108 and dispersant HH2016D.

3. The corrosion resistant Nd-Fe-B permanent magnetic material according to claim 1, characterized in that, The average diameter of the graphene oxide is 3-10 mu m, and the average thickness is 0.55-2.0 nm.

4. The corrosion resistant Nd-Fe-B permanent magnetic material according to claim 1, characterized in that, The preparation method of the 2,3,4,5,6-pentafluorostyrene / 1,3-bis(oxymethylene methyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer comprises the following steps: 2,3,4,5,6-pentafluorostyrene, 1,3-bis(oxymethylene methyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, 2-(1-propen-2-yl)benzo[d]oxazole and an initiator are added into a high-boiling-point solvent, stirring reaction is carried out under an inert gas atmosphere at 60-70 DEG C for 3-5 hours, then the polymer is precipitated in water, the precipitated polymer is washed with ethanol for 3-6 times, and finally drying is carried out in a vacuum drying box at 80-90 DEG C until the weight is constant, so as to obtain the 2,3,4,5,6-pentafluorostyrene / 1,3-bis(oxymethylene methyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione / N-vinylcarbazole / 2-(1-propen-2-yl)benzo[d]oxazole copolymer.

5. The corrosion resistant NdFeB permanent magnetic material according to claim 4, characterized in that, The mass ratio of the 2,3,4,5,6-pentafluorostyrene, 1,3-bis(oxazolidinylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-vinylcarbazole, 2-(1-propen-2-yl)benzo[d]oxazole, initiator, high-boiling-point solvent is 0.5:(0.8-1.2):(3-5):(0.3-0.6):(0.06-0.08):(25-35).

6. The corrosion resistant Nd-Fe-B permanent magnetic material according to claim 4, characterized in that, The initiator is azobisisobutyronitrile; the high-boiling-point solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone; and the inert gas is any one of nitrogen, helium, neon, and argon.

7. The corrosion resistant Nd-Fe-B permanent magnetic material according to claim 1, characterized in that, The other rare earth elements are a mixture of Gd, Tb, and Dy mixed in a mass ratio of 2:1:(1-3).

8. A method of producing the corrosion-resistant Nd-Fe-B permanent magnet material according to any one of claims 1 to 7, characterized by, The method comprises the following steps: In step S1, the components of the neodymium-iron-boron permanent magnet substrate are proportioned by weight percentage, and then a neodymium-iron-boron permanent magnet substrate rapid solidification ingot is prepared by using a vacuum induction rapid solidification ingot preparation technology. In step S2, the micro-powder with an average particle size of 1-4 μm is prepared by using a ball milling or air flow milling process after hydrogen explosion or mechanical crushing. In step S3, the micro-powder is subjected to magnetic field orientation and static pressure forming to obtain a blank neodymium-iron-boron permanent magnet substrate. In step S4, the blank neodymium-iron-boron permanent magnet substrate is obtained after high-temperature sintering and tempering treatment. In step S5, the corrosion-resistant protective coating is obtained by mixing the raw materials of the corrosion-resistant protective coating uniformly, coating the mixture on the outer surface of the neodymium-iron-boron permanent magnet substrate with a coating thickness of 0.2 mm, and then drying.

9. The method of claim 8, wherein the method further comprises the step of: In step S3, the magnetic field orientation and static pressure forming are performed under the conditions of a magnetic field strength of 1-3 T, a pressure of 30-100 MPa, and a nitrogen atmosphere, and then cold isostatic pressing is performed with an isostatic pressing size of 270-320 MPa and a pressing time of 3-5 minutes. ​ 10. The method for preparing the corrosion-resistant NdFeB permanent magnet material according to claim 8, characterized in that, In step S4, the high-temperature sintering is performed in a vacuum sintering furnace with a sintering temperature of 1000-1150 ℃ and a sintering time of 2-4 h; the tempering treatment in step S4 is performed by first performing primary tempering treatment at 850-930 ℃ for 1-3 hours and then performing secondary tempering treatment at 450-600 ℃ for 2-4 hours; and the drying in step S5 is performed at 100-120 ℃ for 3-5 hours.

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